What is the cure for pain and swelling from knee to foot?

My daughter has a problem that she has been dealing with for over a year. We have been to Drs., Vascular, Orthopedic, Gyn, GP, Rheumatoid Arthritis and her cardiologist Dr. and no one can figure out what is wrong. She has had blood work, CAT Scans, MRI's, a nerve test, venus doppler and a bone scan done.
The problem started a year ago. Her left leg only, from knee to foot, is swelling and she is in a lot of pain and unable to walk. In the mornings it is better but progressively gets worse as the day goes on. She has had to use a cane and at times a wheelchair to get around. She has been tested for rheumatoid arthritis, lyme disease, lupus, blood clots, etc. It happens 2-3 times a week. Oddly when she gets her period, her leg is better.
She is 43 years old, white female, does smoke, does not drink alcohol, 5'2" and 125 lbs.
It is very upsetting that no one seems to be able to help her. Do you have any suggestions? We don't where else to turn to.
Thank you,
XXXXX

Brief Answer:
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Detailed Answer:
Hi,
Welcome to XXXXXXX
Unilateral painful leg edema could be an early sign of venous insufficiency or heart failure. It is possible that on clinical examination and Investigations, we may not find any other positive findings. You have not mentioned specifically about the heart disease, she is having, and the medication she is taking for it. Some medication can also cause leg swelling, like Calcium channel blocker, beta blocker, hormones, pain killers, smoking etc. In some clinical situations, we have to make diagnosis by exclusions of certain significant disease. Relief during menstruation also indicates towards venous efficency. There is one very common cause of periodic edema in women younger than 50 Years, is Idiopathic Edema. To confirm this, there are certain tests which you can do at home also. The easy one is , to weigh herself in the morning, after emptying her bladder, and on empty stomach, and then weigh again at bed time, after emptying bladder, If weight gain is more than 700 gms, it indicates Idiopathic edema. Another test is Water Load test. This test will really help you in diagnosing idiopathic edema. I would suggest you to consult your physician again, and request for this test. You c do this test at home also, under your Doctor's supervision.
meanwhile, you ask her to keep her leg elevated wherever possible, and use of some diuretics will be helpful.
Hope you will find this information helpful. If you have any further query, please feel free to ask.
Keep well
Dr H Hamdani